Best time to buy and sell stock

class Solution:
    def maxProfit(self, prices: List[int]) -> int:

        min_price_so_far = float("inf")
        max_profit = -float("inf")

        for i in range(len(prices)):
            if prices[i] - min_price_so_far >=0:
                max_profit_so_far = prices[i] - min_price_so_far
                max_profit = max(max_profit, max_profit_so_far)
            min_price_so_far = min(prices[i], min_price_so_far)

        # also care for edge case when low prices are never observed
        return max_profit if max_profit>0 else 0